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Browse Prior Art Database

Bipolar Bootstrap Circuit

IP.com Disclosure Number: IPCOM000084981D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Schettler, H: AUTHOR

Abstract

Described is a fast driver circuit useful for driving field-effect transistor (FET) memory arrays, in which the collector-base diffusion capacitance of a transistor in the circuit is used to bootstrap the output voltage of the circuit to the value of the supply voltage.

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Bipolar Bootstrap Circuit

Described is a fast driver circuit useful for driving field-effect transistor (FET) memory arrays, in which the collector-base diffusion capacitance of a transistor in the circuit is used to bootstrap the output voltage of the circuit to the value of the supply voltage.

The circuit, shown in the figure, functions as follows. When the input to the base of transistor T1 goes negative the transistor T1 is switched off, causing the voltage applied to the bases of transistor T2 and T3 to rise. This, in turn, causes transistors T2 and T3 to become conductive and to turn on transistors T4, T5 and T6. Transistor T6 causes transistor T7 to become conductive. Simultaneously with the switching off of transistor T1, transistor T8 which held the output to -V is also switched off. Transistor T7 now causes the output to rise towards +V.

High currents of approximately 10 milliamps flow through transistors T4 and T5. Transistor T4 goes into deep saturation because its base-collector diffusion capacitance CD is heavily charged. When this output rises to ground, transistor T5 is switched off by the action of diode D1 and the collector of transistor T4 is caused to be pulled up to +V through resistor R3.

When the collector of T4 rises to +V, the base of transistor T4, and the base of transistor T6, is driven to +V plus the voltage of capacitor CD which is equal to the base-emitter voltage of transistor T3. When this increased voltage is applied to the base...